<?php if (have_posts()) : ?>
    <?php query_posts("category_name=somecat"); ?>
        <?php while (have_posts()) : the_post(); ?>  
 
replace with 
 
<?php if (have_posts()) : ?>
     <?php $paged = (get_query_var('paged')) ? get_query_var('paged') : 1; query_posts("category_name=somecat&paged=$paged"); ?>
        <?php while (have_posts()) : the_post(); ?>

http://stylizedweb.com/2008/08/13/query_posts-pagination-problem/

Use this to fix Pagination Problem on query posts page. This will fix the problem where clicking on the next page keeps showing same posts

Query Posts Pagination Problem Wordpress

wordpress

PHP